German Research Institute of Artificial Intelligence (DFKI), Bremen Lab. Safe and Secure Cognitive Systems Group 15th WSCG International Conference Plzen,

German Research Institute of Artificial Intelligence (DFKI), Bremen Lab. German Research Institute of Artificial Intelligence (DFKI), Bremen Lab. Safe and Secure Cognitive Systems GroupSafe and Secure Cognitive Systems Group

15th WSCG International ConferencePlzen, 31. January 2007

Object Description and Object Description and Decomposition by Symmetry Decomposition by Symmetry

HierarchiesHierarchies

Kai HuebnerKai Huebner

Safe and Secure Cognitive Systems (SSCS)Safe and Secure Cognitive Systems (SSCS)GermanResearch Center for Artificial Intelligence (DFKI)GermanResearch Center for Artificial Intelligence (DFKI)Bremen, Germany.Bremen, Germany.

now at:now at:Computational Vision and Active Perception Lab (CVAP)Computational Vision and Active Perception Lab (CVAP)Royal Institute of Technology (KTH)Royal Institute of Technology (KTH)Stockholm, Sweden.Stockholm, Sweden.



Short MotivationShort Motivation

A Range-Based Symmetry OperatorA Range-Based Symmetry Operator Symmetry HierarchiesSymmetry Hierarchies ExperimentExperiment

ConclusionConclusion

1

OverviewOverview



MotivationMotivation

[Locher & Nodine (1989)][Locher & Nodine (1989)]

MotivationMotivation 2

Architecture

Art

Nature


15th WSCG International ConferencePlzen, 31. January 2007A Range-Based Symmetry Operator

Computation of the whole search space:Computation of the whole search space:

A Range-Based Symmetry OperatorA Range-Based Symmetry Operator

A Dynamic Programming approach.A Dynamic Programming approach.

3






A Range-Based Symmetry Operator 3

































Result:Result:

• Iteration stop at Iteration stop at l = 4 (max)l = 4 (max)

• Mapping index (4 / 4) Mapping index (4 / 4) S = 8 S = 8

Parameters:Parameters:

• Band mask width Band mask width wwBB = 2 = 2

• Absolute threshold Absolute threshold T = 5T = 5

• Weights Weights WWii = 1 = 1

Iterative computation with threshold:Iterative computation with threshold:



[Huebner, Westhoff, Zhang (2005)][Huebner, Westhoff, Zhang (2005)]



Low vertical symmetry (0) High vertical symmetry (w) Low vertical symmetry (0) High vertical symmetry (w)







Low vertical symmetry (0) High vertical symmetry (w) Low vertical symmetry (0) High vertical symmetry (w)



Hierarchies are generally considered w.r.t different operator sizes in Hierarchies are generally considered w.r.t different operator sizes in symmetry strength-based approaches (symmetry strength-based approaches (multi-scalar multi-scalar or or multi-resolutionmulti-resolution):):

Symmetry Hierarchies

[Zabrodsky et al. (1992)][Zabrodsky et al. (1992)]

Multi-scalar hierarchy:Multi-scalar hierarchy:

Symmetry HierarchiesSymmetry Hierarchies

Multi-resolution hierarchy:Multi-resolution hierarchy:

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The range-based operator allows to The range-based operator allows to consider hierarchies of symmetries consider hierarchies of symmetries theirselves instead:theirselves instead:


Symmetry Hierarchies 7






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Symmetry Hierarchies 8

Image decomposition using symmetry hierarchiesImage decomposition using symmetry hierarchies



Platform: Rolland 3, Cognitive Robotics working groupPlatform: Rolland 3, Cognitive Robotics working group Embedded into the SFB/TR8 research projectEmbedded into the SFB/TR8 research project Goal: autonomous, secure and safe driving in dynamic environmentsGoal: autonomous, secure and safe driving in dynamic environments

Rolland 3 Odometry 2x Lenord & Bauer GEL248

Range

Camera IEEE1394 Unibrain Fire-i400 (640 x 480)

ODVS

2x Siemens LS4

SeiwaPro Panorama Eye® HM-N15

Omnidirectional source images

Unwarping into perspective images

Unwarping into panoramic images

9Experiment

ExperimentExperiment



Panoramic image decomposition using symmetry hierarchiesPanoramic image decomposition using symmetry hierarchies

10Experiment


→→

→→




Sector color matching:Sector color matching:

10Experiment


→→

→→




Sector color matchingSector color matching

Result: Intuitive, dynamic image sectoring based on symmetryResult: Intuitive, dynamic image sectoring based on symmetry Future work: Combination of hierarchies & Regional Symmetry Features,Future work: Combination of hierarchies & Regional Symmetry Features,

towards a more general description of symmetric image contenttowards a more general description of symmetric image content

10Experiment


→→

→→



Thanks for your attention!Thanks for your attention!

Documents

German Research Institute of Artificial Intelligence (DFKI), Bremen Lab. Safe and Secure Cognitive Systems Group 15th WSCG International Conference Plzen,